Energy transition contribution
Sun on greenhouse Luttelgeest
Creating large solar fields is usually done on agricultural land. That use is then exchanged for renewable energy production. At Agri PV, it’s different. There are several types of mounting systems that allow both functions to be combined. Putting solar panels on greenhouses can also be seen in this perspective; a form of dual use is created. And that, according to Cees van der Werken, is of increasing interest to greenhouse growers.
‘1 in 3 Dutch greenhouse growers has solar panels. Twenty percent of them are considering investing in it, AgriDirect’s most recent survey found. Strange is not. People working in that sector are also eager to become more sustainable to contribute to the energy transition. Moreover, with today’s astronomical energy prices, there is a real problem. Costs are spiraling out of control, many businesses are struggling. This also leads to an increasing intrinsic need for greater autonomy in energy supply. Putting solar panels on greenhouses on a large scale is a wonderful solution. But it is not without its challenges; in a technical sense and because it interferes with a greenhouse grower’s operations.
ProfiNRG was plenty in the news in mid-2021. The PV installation it realized in Luttelgeest for developer Zonnewijzer went online. The solar power system has as many as 20,000 solar panels good for a peak production of 8.2 megawatts of green power. This is enough to supply 2,200 households with their electricity needs. What makes the project truly special, however, is that the system covers 4 hectares of a greenhouse complex; it was the first time solar panels were routinely installed on greenhouses of this enormous size in the Netherlands. This was made possible in part by the special mounting system ProfiNRG developed for this application.
The construction of greenhouses is usually not designed to support the weight of solar panels, which is not what they are designed for. Thus, placing solar panels above the existing glass is generally not possible due to the limited load-bearing capacity of the greenhouse structure. If you replace the glass with solar panels, then you run into size issues, at least if you don’t use standard solar panels. The mounting system we developed provides the solution. We remove the glass from the roof of the greenhouse. Then we mount our profile system on the rods. In it we slide solar panels. This has several advantages, first and foremost constructively. A PV system should run trouble-free for 25 years and also remain in place during severe weather. Our mounting system provides the necessary robustness. It is also waterproof while facilitating natural ventilation. This is very important because it can get well over 40 degrees in a closed greenhouse. This decreases the efficiency of the panels. In addition, it is a cost-effective system because we work with standard solar panels available on the market and the construction cost is almost the same as that of an average solar field.
Positive business case
The greenhouse complex in Luttelgeest is getting a second life as a green power plant with the installation of solar panels. At the same time, the greenhouse remains available for growing crops. Which ones they will eventually be and how that will play out is still unclear. Time is needed to experiment; after all, the microclimate in the greenhouses changes substantially.
‘With our greenhouse PV system, solar panels can be seamlessly connected,’ Van de Werken said. ‘This allows for maximum solar power generation. This contributes to a positive business case of this type of SDE++ projects. But every advantage has its disadvantage. If you place a large-scale solar energy system on a greenhouse, it will inevitably affect the incidence of light and temperature control. You can play with that, for example by only using solar panels on one side – with our solution, the solar panel can be arranged freely. Still, switching to a more low-quality crop will not infrequently be necessary, and that is of course exciting for an entrepreneur.’
Van de Werken was one of the Dutch pioneers in PV. He started his first solar energy company in 2009. Three years later, he stepped into the solar power business market with ProfiNRG. With that, he initially focused primarily on the agricultural sector under the slogan “Farmer’s Understanding of Solar Panels. He thus followed not only his mind, but also his heart.
‘I am a gardener’s son and not the only one in our company. We have a great affinity with the greenhouse industry, know the challenges and know what is going on. At a time when energy costs weigh so heavily on business operations, PV is a great way to generate additional income. It is then searching for an optimal balance between the two functions, and that is where ProfiNRG is happy to help. There are also many greenhouse growers who are considering quitting, or have already done so. Implementing a solar energy system on a greenhouse is also worthwhile in those cases. With our system, there can be a good earning model from as little as 1 acre.’